Delay locked loops (DLL) reside in many integrated circuits for delaying an external signal to obtain an internal signal. The internal signal usually serves as a reference signal for the integrated circuits instead of the external signal because the internal signal matches internal operating conditions of the integrated circuits, such as process, voltage, and temperature, better than the external signal does.
A typical DLL has number of delay elements, forming a delay line. The external signal propagates through a certain number of activated delay elements in the delay line to become the internal signal. The activated delay elements toggle (switch) in every cycle of the external signal. Each delay element consumes power when it toggles. The power consumption is proportional to the number of toggles. In some cases, improving the power consumed by the DLL is necessary.